Elimination of abrasion of well tubing by production fluid containing abrasive material



INVENTOR. R.L. FLOWERS WM 3 A T TORNE Ks y 1962 R. L. FLOWERSELIMINATION OF ABRASION OF WELL TUBING BY PRODUCTION FLUID CONTAININGABRASIVE MATERIAL Filed Dec. 29, 1958 3,034,912 ELIMINATION OF ABRASIQNF WELL TUBWG BY PRODUCTIDN FLUID CQNTAINING ABRA- SIVE MATERIAL RichardL. Flowers, Houston, Tex, assiguor to Phillips Petroleum Company, acorporation of Delaware Filed Dec. 29, B58, Ser. No. 783,448 14 Claims.(Q1. 166-243) This invention relates to fluid production from a deepwell. In one aspect, it relates to protection of a production tubingadjacent an upper producing formation of a dually completed well inwhich the fluid entering the well bore from the upper formation at highvelocity contains an abrasive and abrades or erodes the tubing throughwhich fluid from the lower formation is produced.

:In wells which are completed in more than one formation, it isnecessary to place one or more joints of tubing opposite the upperproducing formation. In a dually completed well, productiontubingextending to a lower producing formation sometimes becomes abradedor eroded at the level of the perforations of the upper producingformation. This tubing erosion results from the presence of abrasivematerial in the fluid produced from the upper formation. In case atubing, which is produc ing fluid from the lower of two formations,becomes abraded to such an extent that an opening is produced, fluidfrom the upper formation enters the tubing through the opening and isproduced in the tubing along with fluid from the lower formation. As isknown, it is necessary to produce fluid from several formationsseparately because in some instances fluid pressure from one formationmay be sufficiently higher than the fluid pressure from the secondformation that fluid from the first formation enters the secondformation thereby preventing fluid production from the second and lowerpressure formation. Failures of production tubing at the level of theupper producing formation have occurred. Pulling of well tubings andreplacing of the damaged sections of tubings are expensive operations.Various attempts have been made to solvethis erosion problem. Joints oftubings which are to be positioned at the level of the upper fluidproducing formation have been coated with solid coatings such as rubber,neoprene, lead, ceramic material, etc., with varying degrees of success.The erosion is particularly severe in cases when nearly all of theperforations of the casing adjacent the upper formationbecome pluggedthereby causing the remaining unplugged perforations to admit fluidpressure under extremely high velocity. Fluid containing such abrasivematerial as sand from the formation entering the well bore through asmall number of easing perforations enters at a much higher velocitythan if there is a larger num- 7 her of open perforations.

The present invention is directed to a more feasible solution of thiserosion problem than the provision of the solid coating materialsmentioned hereinabove being disposed on the well tubing. This solutioninvolves use of a series of loosely fitting rings disposed around thejoint of production tubing at the level of the perforations of the upperof two fluid producing formations. The outer faces of these looselyfitting rings are provided with curved surfaces or vanes so arrangedthat fluid impinging against the vanes will rotate these looselyfittings rings around the well tubing. The fluid containing abrasivematerial entering the well bore gives up a portion of its kinetic energyin rotating these rings thereby reducing the velocity of the fluid andsimultaneously reducing the abrading action of the fluid. The rings areheld in place by upsets or couplings of the tubing.

An object of this invention is to provide relatively inexpensive meansand methods for the elimination of abraassists Patented May I5, 1962sion or erosion of a well tubing adjacent an upper producing highpressure formation in a dually completed well in which the fluid fromthe upper formations contains an abrasive. tion will be realized uponreading the following description which, taken with the attacheddrawing, forms apart of this specification.

In the drawing, FIGURE 1 illustrates the installation of the apparatusof my invention in a dually completed well. FIGURE 2 is a view taken onthe line 2-2 of FIGURE 1. FIGURE 3 is a view, partly in section, takenon the line 33 of FIGURE 2. FIGURES 4, S, 6,.7 and 8 illustrateadditional embodiments of my invention. FIGURE 9 is a view taken alongthe line 99 of FIGURE 8. FIGURE 9a is a sectional view of a portion ofanother embodiment of the invention. FIGURE 10 is a sectional view takenalong the line 10-16 of FIGURE 9a.

In reference to the drawing and specifically to FIGURE 1, referencenumeral lll'identifies the well bore provided with a casing 12. Thiswell bore and casing extend through two fluid producing formations 13and 14. The casing adjacent the upper of the two producing formutions isprovided with perforations l5 and is provided with perforations 16adjacent the lower producing formation. A packer 20 seals formation 14from formation 13 so that fluid from one of the formations cannot enteror be mixed with fluid from the other of the formations. A productiontubing 17 is disposed in the well as illustrated. Near the lower end ofthis production tubing 17 is disposed a ring assembly 25 of myinvention. The lower end of the tubing extends through packer 20 in sucha manner that the ring assembly 25 does not come in contact with theinner walls of the casing 12.

A second production tubing 18 is provided as illustrated for passage offluid from the upper formation 13 to the well head. Tubingslti and 17communicate with pipes 23 and 24, respectively, at the well head forpassage of production from the two formations to such disposal asdesired. Reference numeral 22 identifies the head of the casing. Asecond packer I9 is illustrated as sealing off the upper formation fromthe well head. This packer also holds tubings 17 and I8 rigidly inplace. On reference to FlGURE 2, which is a view taken on the line 2-2of FIGURE 1, it is seen that the outer periphery of ring 26 is made ofvanes 27, which are herein more accurately described or termed asdeflector vanes. The sides of vanes 27 are curved deflector sidesurfaces 28 and these side surfaces are so shaped that fluid enteringwell bore 11 through casing perforations 15 causes the rings 26 torotate in one direction or the other. These curved surfaces act torotate these rings in a manner more or less similar to the action ofbuckets on water wheels such as the Pelton type water wheel. It isrealized that fluid passing at a high velocity through perforations 15can enter the casing as a jet stream, or it may spread out more or lessin the form of a cone. The particular form that the fluid acquires onentering the casing depends at least in part on the shape and theorientation of the perforations 15. However, the fluid which enters thecasing enters at a high velocity and this high velocity is reduced byimpinging on the curved surfaces 28 thereby causing the rings 26 torotate. Some of these rings may rotate in one direction while others mayrotate in the same direction or in the reverse direction. The annulusinside casing 12 at the level of the upper producing formation 13 isidentified in FIGURE 1 by reference numeral 21. Reference numeral 33identifies the upset ends of adjacent tubing joints which contain maleand female threaded sections for attaching one joint of tubing to theother. This upset portion 33 serves as a collar or as a retainer toprevent downward move- Other objects and advantages of this invenment ofthe ring assembly 25. As illustrated in FIGURE 3, the upper and lowerend surfaces of the vanes 27 terminate as curved surfaces 52a so thatfluid impinging at these surfaces will be deflected and thus reduced invelocity to minimize the abrasion effect of the incoming fluid. However,fluid impinging against surfaces 52a does not assist in rotation of therings 26. In the embodiment illustrated in FIGURE 3, the rings 26 areconstructed of a polyethylene material. The inner diameter of rings 26is made greater than the outer diameter of tubing 17 with the provisionof an annulus 29 therebetween so that the ring can rotate freely aroundthe tubing. In one instance, a polyethylene ring 26 or a ring made ofother suitable plastic, such as Teflon, a polymeric fluorocarbon, issplit at 32 so that the rings can be spread somewhat and raised upwardover the upset portion 33 of the tubing prior to running of this tubinginto the well.

In FIGURE 8 is illustrated rings 46 also made of a plastic material.These rings illustrated in this figure are not provided with the curvedtop and bottom surfaces corresponding to surfaces 52a of FIGURE 3 butthey are merely square shouldered. Such rings are, if desired, split asthe ring illustrated in FIGURE 4 for sliding over the upset ends of ajoint of tubing. Ring 46 is provided with a beveled surface 47 to bearagainst a beveled surface 48 of a joint of tubing to prevent theassembly of rings from sliding downward on the tubing. These rings arealso provided with a flange 50, as illustrated, for assisting inpreventing abrasive material from finding its way through the joint atwhich an upper ring contacts a lower ring. Abrasive material which wouldfind its way to the annulus 49 between rings 46 and tubing 17 wouldcertainly abrade the tubing as the rings rotate. This annulus providesfor free rotation of the rings around the tubing. As mentionedhereinabove, rings 46 may all rotate in one direction or some may rotatein one direction and the remainder in the opposite direction. Rings 46are provided with curved side surfaces 53 similar ot side surfaces 28 ofFIGURE 2 for causing rotation of the rings of the assembly. These sidesurfaces 53 are illustrated in FIGURE 9. The rings 46 of FIGURES 9 andare also made of such a plastic material as mentioned hereinabove. InFIGURE 5 is illustrated another embodiment of deflector ring of myinvention more or less similar to the ring 46 of FIGURE 8 but rings 31of FIGURE 5 are provided with upper and lower curved surfaces 52b. Thesecurved surfaces 52b serve the same purpose as curved surfaces 52a ofFIGURE 3. Ring 31 is provided with beveled surface 34 which contactswith beveled surface 35 on the tubing 17 to support the ring assembly.As illustrated in FIGURE 5, a threaded section 36 is provided forjoining one joint of tubing with another.

In FIGURE 6is illustrated another embodiment of deflector ring of myinvention in which the outer portion of the ring is composed of a metalsuch as steel while the inner portion of the ring is made of a plasticmaterial such as a polyethylene 38. This material 38 on the inside ofthe ring serves as a hearing or bushing for rotation of the ring aroundtubing 17. Since a portion of this combination metal and plastic ring isnot expandable for sliding upward and over an upset section as section33 of FIGURE 5, the rings are placed around the tubing 17 and then ametal ring 39 is placed as illustrated in FIGURE 6 and attached by welds40. The plastic ring 38 is sufficiently larger in inside diameter thanthe outer diameter of tubing 17 to provide an annulus 51 for freerotation of the ring around the tubing. The steel portion 37 of thisring is provided with upper and lower curved surfaces 52 and side curvedsurfaces similar to surfaces 28 of FIGURES 2 and 3 for deflection of theincoming fluid containing abrasive. In FIGURE 7 is illustrated acombination deflector ring more or less similar to that illustrated inFIGURE 6. In this figure,

a pair of adjoining rings is shown to illustrate the positioning of onering against another ring when the rings are made of the outer metal andthe inner plastic. The metal portionis provided with shaped deflectorveins 42 which have top and bottom curved surfaces 520 as well as sidecurved surfaces similar to those illustrated in FIG- URES 2, 3, 9 and9a. In FIGURE 7, it is intended that upper plastic bushing 43 bearsnugly against the lower plastic bushing 43 so that if these two ringsrotate in opposite directions or at different rotational rates in thesame direction the main bearing surface is that between the two plasticbushings. However, the lower surface of the upper metal deflector vane42 and the upper surface of the lower metal vane 42 may fit rathersnugly so that solid material cannot easily find its way between thesetwo metal surfaces. Metal flanges 45' are positioned with respect to thebushings 43 as illustrated. As will be realized by those skilled in theart the flange 44 of plastic when Wet with well fluid permits the upperbushing 43 along with its ring to rotate rather freely. The innerdiameters of bushings 43 are made slightly larger than the outerdiameter of the tubing 17 so that the rings easily rotate therearound.Reference numeral 41 identifies this clearance or annulus.

In FIGURES 9a and 10 are illustrated an embodiment of deflector ring inwhich the ring is made entirely of metal. In these figures referencenumeral 54 identifies the metal ring While reference numeral 55identifies the protruding vane having curved deflector side surfaces 56similar to those of the other embodiments of this invention.

I find that a plastic material which is suitable for production of thedeflector vanes and also for the ring bearings or bushings is a highdensity polyolefin, such as a polyethylene. This polyethylene which issuitable for the production of these apparatus parts has a molecularweight in the range of 25,000 to 200,000 or higher, a density of from0.940 to 0.980 gram per cubic centimeter and a crystallinity of at leastpercent. A full description of the method for preparation of thisplastic material is given in U.S. Patent 2,825,721. Briefly, thisprocess involves polymerizing ethylene at a polymerization temperaturein the range of to 500 F., with a catalyst active for suchpolymerization and consisting essentially of chromium oxide supported onat least one material selected from the group consisting of silica,alumina, zirconia and thoria, at least part of the chromium being in thehexavalent state at the initial contacting of hydrocarbon with saidcatalyst, and recovering a resulting solid polymer. After production ofthe solid polyethylene, the rings, bearings and any other apparatusparts desired to be made of this material are extrusion molded into theproper shapes.

As stated, the density of this polyethylene material is between about0.940 and 0.980 gram per cubic centimeter and the density is ordinarilydetermined on a sample of the mass polyethylene in non-filamentary form.The sample is prepared for the determination of density by compressionmolding of the polyethylene at a temperature of 340 F. in a moldprovided with a water jacket through which water can be circulated. Thesample is maintained at about 340 F. until it is completely molded. Itis then cooled from 340 to 200 F. at the rate of approximately 10Fahrenheit degrees per minute. Water is then circulated through the moldto continue the cooling to F., the rate not exceeding 20 Fahrenheitdegrees per minute. The polyethylene is then removed from the mold andcooled to room temperature. A small piece of the solidified polyethyleneis cut from the compression molded sample and inspected to make surethat it is free of voids and that it has a sufiiciently smooth surfaceto prevent the trapping of air bubbles on its surface. The small sampleis placed in a 50 ml. glass stoppered graduate. Carbon tetrachloride andmethylcyclohexane are then allowed to run into the graduate fromseparate burettes in such proportions that the sample is suspended inthe mixed solution, i.e., it neither floats nor sinks. The graduate isshaken during the addition of the liquid in order that the two liquidsmix thoroughly. A total liquid volume of to ml. is required. After theliquids have been so proportioned that the polyethylene is suspendedtherein without sinking or floating, the density of the liquid mixtureis equal to the density of a solid polyethylene. The polyethylene isthen removed from the liquid and a portion of the liquid mixture ofcarbon tetrachloride and methylcyclohexane is transferred to a Westphalbalance and the specific gravity of the liquid is measured at atemperature in the range of 73 to 78 F. This specific gravity is equalto the specific gravity of the polyethylene. For most practicalpurposes, the specific gravity is considered identical to the density.However, if a precise conversion to actual density units, grams percubic centimeter, is desired, this is readily referable to water at 4 F.by calculations which will readily be evident to those skilled in theart. The precision of a single specific gravity determination isordinarily within i.0002. The molecular weight is determined bymeasuring the .time required for a filtered solution of 0.1000 gram ofthe polyethylene in 50 ml. of tetralin (measured at room temperature,that is, about 75 F.) to run through the marked length on a size 50(0.8-3.0 centistokes) Ostwald-Fenske viscosimeter at a temperature of130 C. (the viscosimeter being immersed in a thermostatically controlledoil bath) and measuring also the time required for an equal volume oftetralin containing no polyethylene to run through the same distance onthe same viscosimeter. The molecular weight is calculated in accordancewith the following formula:

where K equals 24,450, C equals 0.183, Vr equals time, in seconds,required for solution to run through the viscosimeter divided by thecorresponding time required the polymer-free tetralin, both at 130 C. Asingle determination of molecular weight originally has a precision of$1,000 molecular weight units.

The crystallinity of this polyethylene is determined by nuclear magneticresonance. The percentage crystallinity represents the percentage byweight of the total polymer which is crystalline rather than amorphous.

The deflector rings of my invention are made of such metal as willwithstand abrasion at least reasonably well. The rate or mass of theserotatable ring should be so selected that the rings are rather easilyrotated by the jetting well fluid yet they must be sufficiently heavy toabsorb at least a considerable portion of the kinetic energy of thestream or streams of well fluid entering through the casingperforations. When these rings are too light they rotate too easilyunder the influence of the inflowing well fluid and do not absorb muchkinetic energy nor reduce the velocity of the inflowing fluid and inthis manner actually they do not serve the intended purpose. When therings are too heavy they rotate with difficulty and are more or lessequivalent to merely a stationary tubing and continued jetting of thewell fluid through the perforations onto the fins of the rings with therings not rotating will in due time abrade the fins, the rings thenmerely acting as mechanical protectors of the tubing. Upon continued usein this manner, the rings wear or are abraded and ultimately the tubingwill be damaged by the incoming well fluid. The rings in this case servelittle purpose.

The rings should fit loosely around the tubing so that there will not beunwarranted abrasion between the plastic ring, or inner ring and themetal tubing as the ring rotates. Clearances of the order of 0.05 to 0.1inch or greater are usually ample for free rotation of the ring aroundthe tubing. In some instances, clearances, i.e., the inside diameter ofthe ring minus the outside diameter of the 6 tubing, are greater than0.1. inch, and in other instances less than 0.05 inch.

Other polyolefins suitable for production of the deflector vanes hereindisclosed possess densities of about 0.90 to 0.92, crystallinities of atleast about percent, and molecular weights in the range of about 25,000to 200,000. A method for preparation of polyolefin plastic material isgiven in Belgian Patents 533,362 and 538,782.

While certain embodiments of the invention have been described forillustrative purposes, the invention obviously is not limited thereto.

I claim:

1. An apparatus for minimizing erosion of a portion of a deep well fluidproduction assembly disposed in a well through a high pressure fluidproducing formation, said formation being adapted to inject fluidcontaining an abrasive into said well at high velocity comprising, incombination, a well production tubing extending from the head of saidwell through a high pressure fluid producing formation to a level belowsaid formation, said tubing being adapted for production of well fluidfrom a formation below the aforesaid formation, a packer set in saidWell intermediate said formations, at least one ring disposedconcentrically and rotatably around said tubing throughout the areaexposed to said high pressure fluid of the first mentioned formation, aplurality of vanes disposed at spaced intervals on the outer peripheryof said ring and extending outward therefrom, the longitudinal axes ofsaid vanes being parallel to the axis of said tubing, said vanes havinginwardly curved side surfaces in such a manner as to absorb energy fromsaid well fluid containing abrasive on being injected into said well athigh velocity, the absorbed energy being transformed into rotationalenergy of said ring thereby reducing abrasion of said tubing by the highvelocity fluid containing abrasive, and means retaining said ring at thelevel of the first mentioned formation.

2. An apparatus for minimizing erosion of a portion of a deep well fluidproduction assembly disposed in a well through a high pressure fluidproducing formation, said formation being adapted to inject fluidcontaining an abrasive into said well at high velocity comprising, incombination, a well production tubing extending from the head of saidwell through a high pressure fluid producing formation to a level belowsaid formation, said tubing being adapted for production of well fluidfrom a formation below the aforesaid formation, a packer set in saidwell intermediate said formations, a plurality of rings disposedconcentrically and rotatably around said tubing throughout the areaexposed to said high pressure fluid of the first mentioned formation, aplurality of vanes disposed at spaced intervals on the outer peripheryof each of said rings and extending outward therefrom, the longitudinalaxes of said vanes being parallel to the axis of said tubing, said vaneshaving inwardly curved side surfaces in such a manner as to absorbenergy from said well fluid containing abrasive on being injected intosaid well at high velocity, the absorbed energy being transformed intorotational energy of said rings thereby reducing abrasion of said tubingby the high velocity fluid containing abrasive, and means retaining saidrings at the level of the first mentioned formation.

3. The apparatus of claim 2 wherein said plurality of rings extend adistance along said tubing approximately equal to the thickness of saidhigh pressure fluid producing formation.

4. An apparatus for minimizing erosion of a portion of a deep well fluidproduction assembly disposed in a well through a high pressure fluidproducing formation, said formation being adapted to produce fluidcontaining an abrasive comprising in combination, a casing disposed insaid well, a well production tubing in said casing extending from thewell head through said high pressure fluid producing formation to alevel below said formation, said tubing being adapted for production ofwell 7 fluid from a formation below the aforesaid formation, a packerset in said casing intermediate said formations, said casing containingperforations at the level of said high pressure formation, a pluralityof rings disposed concentrically and rotatably around said tubingthroughout the area exposed to said high pressure fluid injected throughsaid perforations, a plurality of vanes disposed at spaced intervals onthe outer periphery of each of said rings and extending outwardtherefrom, the longitudinal axes of said vanes being parallel to theaxis of said tubing, said vanes having inwardly curved side surfaces insuch a manner as to absorb energy from said well fluid containingabrasive on being injected into said casing through at least oneperforation of said plurality of perforations at high velocity, theabsorbed energy being transformed into rotational energy of said ringsthereby reducing abrasion of said tubing by the high velocity of fluidcontaining abrasive, and means supported by said tubing retaining saidrings at the level of said perforations.

5. The apparatus of claim 4 wherein said plurality of rings extend froma level below the lowermost of said perforations to a level above theuppermost of said perforations.

6. The apparatus of claim 1 wherein said ring is a ring of plasticmaterial.

7. The apparatus of claim 1 wherein said ring is a metal ring.

8. The apparatus of claim 1 wherein said ring comprises a pair ofmutually nonrotatable concentric rings, the inner ring of said pair ofrings being a bearing of a plastic and the outer ring of said pair beingof a metal.

9. The apparatus of claim 6 wherein said plastic material comprises apolyethylene having a molecular weight in the range of 25,000 to200,000, a density of from 0.940 to 0.980 grams per cubic centimeter anda crystallinity of at least 90 percent.

10. The apparatus of claim 1 wherein the rings comprise a plasticmaterial and said plastic material comprises a polyethylenehaving amolecular weight in the range of 25,000 to 200,000, a density of from0.940 to 0.980 grams per cubic centimeter and a crystallinity of atleast 90 percent.

11. The apparatus of claim 8 wherein said plastic comprises apolyethylene having a molecular Weight in the range of 25,000 to200,000, a density of from 0.940 to 0.980 gram per cubic centimeter anda crystallinity of at least 90 percent.

12. An apparatus for minimizing erosion of a portion of a deep wellfluid production assembly disposed in a well through a high pressurefluid producing formation,

said formation being adapted to produce fluid containing an abrasivecomprising in combination, a casing disposed in said well, a wellproduction tubing in said casing extending from the well head throughsaid high pressure fluid producing formation to a level below saidformation, said tubing being adapted for production of well fluid from aformation below the aforesaid formation, a packer set in said casingintermediate said formations, said casing containing at least oneperforation at the level of said high pressure formation, at least onering disposed concentrically and rotatably around said tubing throughoutthe area exposed to said high pressure fluid injected through saidperforation, a plurality of vanes disposed at spaced intervals on theouter periphery of said ring and extending outwardly therefrom, thelongitudinal axes of said vanes being parallel to the axis of saidtubing, said vanes having inwardly curved side surfaces in such a manneras to absorb energy from said well fluid containing abrasive on beinginjected into said casing through said perforation at high velocity, theabsorbed energy being transformed into rotational energy of said ringthereby reducing abrasion of said tubing by the high velocity fluidcontaining abrasive, and means supported by said tubing retaining saidring at the area exposed to said high pressure fluid.

13. The apparatus of claim 5 wherein said rings are rings of plasticmaterial and said plastic material comprises a polyethylene having amolecular weight in the range of 25,000 to 200,000, a density of from0.940 to 0.980 gram per cubic centimeter and a crystallinity of at leastpercent.

14-. The apparatus of claim 12 wherein said ring is a ring of plasticmaterial and said plastic material comprises a polyethylene having amolecular weight in the range of 25,000 to 200,000, a density of from0.940 to 0.980 gram per cubic centimeter and a crystallinity of at least90 percent.

References Cited in the file of this patent UNITED STATES PATENTS1,272,253 Green July 9, 1918 1,716,015 Tuthill June 4, 1929 2,005,767Zublin June 25, 1935 2,552,716 Holland May 15, 1951 2,857,931 LawtonOct. 28, 1958 2,925,097 Duesterberg Feb. 16, 1960 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 3,034,912 May 15 1962Richard L. Flowers It is hereby certified that error appears in theabove numbered patters Patent should read as ent requiring correctionand that the said Let corrected below.

4 Column 8 line 27, for the claim reference numeral "5" read Signed andsealed this 2nd day of October (SEAL) Attest:

DAVID L. LADD ERNEST W. SWIDER Attesting Officer Commissioner of Patents

1. AN APPARATUS FOR MINIMIZING EROSION OF A PORTION OF A DEEP WELL FLUIDPRODUCTION ASSEMBLY DISPOSED IN A WELL THROUGH A HIGH PRESSURE FLUIDPRODUCING FORMATION, SAID FORMATION BEING ADAPTED TO INJECT FLUIDCONTAINING AN ABRASIVE INTO SAID WELL AT HIGH VELOCITY COMPRISING, INCOMBINATION, A WELL PRODUCTION TUBING EXTENDING FROM THE HEAD OF SAIDWELL THROUGH A HIGH PRESSURE FLUID PRODUCING FORMATION TO A LEVEL BELOWSAID FORMATION, SAID TUBING BEING ADAPTED FOR PRODUCTION OF WELL FLUIDFROM A FORMATION BELOW THE AFORESAID FORMATION, A PACKER SET IN SAIDWELL INTERMEDIATE SAID FORMATION, AT LEAST ONE RING DISPOSEDCONCENTRICALLY AND ROTATABLY AROUND SAID TUBING THROUGHOUT THE AREAEXPOSED TO SAID HIGH PRESSURE FLUID OF